Recent observations in this laboratory have demonstrated that circulating stem cells (CFU-C) increase markedly following intensive chemotherapy in patients with cancer. Because of this expansion in the peripheral blood stem cell pool, it may be feasible, using simple pheresis techniques, to obtain a sufficient quantity of cells for investigations in autologous stem cell reconstitution. In this proposal we intend to 1) determine the time of appearance of maximum CFU-C activity in the peripheral blood of patients undergoing chemotherapy, 2) investigate techniques for optimum procurement and preservation of these cells, 3) study the conditions under which reconstitution can be consistently achieved by infusion of these cells in humans and 4) determine by clinical trial the value of autologous stem cell support in enhancing the therapeutic effectiveness of chemotherapy.